Preparation method of 1, 3, 6-hexane trinitrile

Abstract

The invention relates to a preparation method of 1, 3, 6-hexane trinitrile, and belongs to the technical field of organic synthesis. The preparation method comprises the following steps: S1, preparing 1-amino-2-cyano-1-cyclopentene by taking adiponitrile as a raw material under a non-nucleophilic strong alkali condition, and purifying and drying the 1-amino-2-cyano-1-cyclopentene; s2, in the presence of solid alkali, 1-amino-2-cyano-1-cyclopentene and the dried acrylonitrile are subjected to a reaction, and a reaction solution is obtained; and S3, carrying out dehydration treatment on the 1, 3, 6-hexanetricarbonitrile reaction liquid by using a dehydrating agent, and finally carrying out post-treatment purification to obtain a 1, 3, 6-hexanetricarbonitrile product. In the step S2, the solid alkali is at least one of a hydrotalcite catalyst, HND-63 and HND-64. According to the preparation method disclosed by the invention, the 1, 3, 6-hexanetricarbonitrile product with high purity, low chroma and high yield can be obtained, and the product is more stable after being placed for a long time and is more suitable for industrial application.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of 1,3,6-hexanetricarbonitrile, belonging to the technical field of organic synthesis. BACKGROUND

[0002] Multi-carbonyl compounds are usually used as positive electrode protection additives added to electrolyte, which can continuously protect the positive electrode and prevent electrolyte components from being oxidized on the surface of the positive electrode at high voltage, thereby improving the cycle performance of lithium ion batteries. In particular, 1,3,6-hexanetricarbonitrile has a significant effect on improving the high-voltage stability of the battery, and has strong stability at high and low temperatures, so as an additive of lithium battery electrolyte, it has a great effect on improving the performance of the battery.

[0003] There are many documents and patents reported on the preparation method of 1,3,6-hexanetricarbonitrile. Among them, the patent application with publication number US20200369602A introduced by Ausimont Company introduced a method of obtaining 1,3,6-hexanetricarbonitrile by rectifying and purifying by-products in the production process of adiponitrile, which requires multiple rectification towers with high separation efficiency, the efficiency is low, and the purity of the final product is only about 99.2%; The patent application with publication number CN105037203A introduced by Hebei Shengtai Company introduced a method of preparing 1,3,6-hexanetricarbonitrile by reacting 1,4-dichloro-2-butene with sodium cyanide, which uses highly toxic cyanide as raw material, which has great safety hazards; The patent application with publication number CN111517986A introduced by Shanghai Rukun Company introduced a method of using ethyl cyanoacetate and the like as raw materials to prepare hexanetricarbonitrile with carboxylic acid ester, and then decarboxylating to prepare the product, which has harsh process conditions and low atom utilization rate; The patent with publication number CN104387291B introduced by Suzhou Yakete Science and Technology introduced a method of using adiponitrile as raw material, first preparing 1-amino-2-cyano-1-cyclopentene, then reacting with acrylonitrile in the presence of sodium hydroxide aqueous solution and phase transfer catalyst to obtain a crude product, then using hydrogen peroxide, sodium hypochlorite and the like as oxidizing agent to oxidize the crude product, and then filtering, washing, concentrating and the like to obtain 1,3,6-hexanetricarbonitrile, which has complicated steps, low yield and poor purity; The patent application with publication number CN119661401A introduced by Suzhou Yakete Science and Technology improved the purification method, extracted the crude product with anhydrous ethanol and the like, then subjected to two thin film distillations to obtain 1,3,6-hexanetricarbonitrile after distillation, then added ethyl acetate for decolorization, filtered the decolorized product to remove the solvent and dried, which still has complicated steps, and after distillation and decolorization, it is difficult to completely remove the activated carbon by filtration, so there may be activated carbon residues in the product, the high-temperature time in the solvent removal process is long, which increases the risk of product deterioration.

[0004] In summary, there are many reports on the preparation method of 1,3,6-hexane tricyanide, but there are still some problems in its preparation and purification process, such as difficult to obtain raw materials, complicated steps, low yield, low purity, poor color and other problems; and most of the synthesis process, there are trace amounts of amide and ether impurities in the final product, which can easily deteriorate and discolor after long-term storage; therefore, a preparation and purification method of 1,3,6-hexane tricyanide is needed, which can meet the requirements of battery grade 1,3,6-hexane tricyanide in purity, color, moisture and other indicators, and the product can be stored for a long time to meet the industrial application. SUMMARY

[0005] The present application provides a preparation method of 1,3,6-hexane tricyanide, which uses solid base as catalyst and dried acrylonitrile as raw material, effectively controls the generation of 2-cyanoethyl ether and amide impurities, and further converts amide impurities into products by using dehydrating agent, thereby obtaining high-purity, low-color, high-yield products, and the products are more stable after long-term storage, which is more suitable for industrial application.

[0006] The technical scheme for solving the above technical problems is as follows: a preparation method of 1,3,6-hexane tricyanide, the preparation method is:

[0007] S1, under the condition of non-nucleophilic strong base, 1-amino-2-cyano-1-cyclopentene is prepared from hexanedinitrile and dried;

[0008] S2, 1-amino-2-cyano-1-cyclopentene reacts with dried acrylonitrile in the presence of solid base to obtain a reaction solution;

[0009] S3, using a dehydrating agent to dehydrate the 1,3,6-hexane tricyanide reaction solution, and finally purifying the 1,3,6-hexane tricyanide product by post-treatment.

[0010] On the basis of the above technical scheme, the present application can also be improved as follows:

[0011] Further, in step S1, the non-nucleophilic strong base is at least one of potassium tert-butoxide, sodium tert-butoxide, potassium tert-amylate, sodium tert-amylate, sodium hydride and sodium amide.

[0012] Further, in step S1, the molar ratio of the non-nucleophilic strong base to hexanedinitrile is (1-1.5):1.

[0013] Further, in step S1, the reaction temperature is 40-100℃.

[0014] Further, in step S2, the solid base is at least one of hydrotalcite catalyst, HND-63 and HND-64;

[0015] The water content in the dried acrylonitrile is less than or equal to 500 ppm.

[0016] Further, in step S2, the reaction temperature is 30-80℃.

[0017] Further, in step S2, the molar ratio of 1-amino-2-cyano-1-cyclopentene to the dried acrylonitrile is 1:(0.9-1.3).

[0018] The mass ratio of 1-amino-2-cyano-1-cyclopentene to the solid base is 1:(0.02-0.2).

[0019] Further, in step S3, the dehydrating agent is at least one of phosphorus pentoxide, phosphorus oxychloride and thionyl chloride.

[0020] Further, in step S3, the mass ratio of 1,3,6-hexanetricarbonitrile to the dehydrating agent is 1:(0.01-0.05).

[0021] In step S3, the reaction temperature is 50-120℃.

[0022] Further, in step S3, the post-treatment purification process is as follows: after the dehydration treatment, water washing is performed until neutral, and after the solvent is removed, distillation is performed, the pressure of the first-stage distillation is 5-30 Pa, the temperature is 150-190℃, the obtained heavy component is subjected to second-stage distillation, the pressure of the second-stage distillation is 5-30 Pa, the temperature is 190-230℃, and the obtained light component is the 1,3,6-hexanetricarbonitrile product.

[0023] The 1,3,6-hexanetricarbonitrile product prepared by the method has the following advantages:

[0024] The method for preparing 1,3,6-hexanetricarbonitrile according to the present application uses a solid base as a catalyst and dried acrylonitrile as a raw material, effectively controls the generation of 2-cyanoethyl ether and amide impurities, improves the product purity and stability, further converts the amide impurities into the product by using a dehydrating agent, and has a high product yield; after distillation, the product is a qualified product without the need for further decolorization and solvent removal, thereby reducing the risk of product deterioration and simplifying the process flow.

[0025] The method for preparing 1,3,6-hexanetricarbonitrile according to the present application can obtain a 1,3,6-hexanetricarbonitrile product with high purity and low colority (the product purity is not less than 99.90%), and greatly improves the product stability, thereby meeting the application requirements of lithium batteries. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The GC-MS spectrum of the 1,3,6-hexanetricarbonitrile prepared in Example 1;

[0027] Figure 2The HNMR spectrum of the 1,3,6-hexanetricarbonitrile prepared in Example 1 is shown in Figure 1. 13 The HNMR spectrum of the 1,3,6-hexanetricarbonitrile prepared in Example 1 is shown in Figure 1.

[0028] Figure 3 The HNMR spectrum of the 1,3,6-hexanetricarbonitrile prepared in Example 1 is shown in Figure 1. 1 The HNMR spectrum of the 1,3,6-hexanetricarbonitrile prepared in Example 1 is shown in Figure 1. DETAILED DESCRIPTION

[0029] In order to make the above objectives, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below. In the following description, a large number of specific details are set forth in order to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the scope of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0031] A preparation method of 1,3,6-hexanetricarbonitrile, the preparation method comprising the following steps:

[0032] S1, preparing 1-amino-2-cyano-1-cyclopentene from dicyanohexane under the condition of a non-nucleophilic strong base and drying and purifying the 1-amino-2-cyano-1-cyclopentene;

[0033] S2, reacting the 1-amino-2-cyano-1-cyclopentene with dried acrylonitrile in the presence of a solid base to obtain a reaction solution;

[0034] S3, dehydrating the 1,3,6-hexanetricarbonitrile reaction solution by using a dehydrating agent, and finally purifying the 1,3,6-hexanetricarbonitrile product through post-treatment.

[0035] On the basis of the above technical solution, the present application can also be improved as follows:

[0036] Specifically, in step S1, the non-nucleophilic strong base is at least one of potassium tert-butoxide, sodium tert-butoxide, potassium tert-amylate, sodium tert-amylate, sodium hydride, and sodium amide.

[0037] Specifically, in step S1, the molar ratio of the non-nucleophilic strong base to dicyanohexane is (1-1.5):1.

[0038] Specifically, in step S1, the reaction temperature is 40-100°C.

[0039] Specifically, in step S2, the solid base is at least one of hydrotalcite catalyst, HND-63, HND-64.

[0040] The water content in the dried acrylonitrile is ≤500ppm.

[0041] Preferably, in step S2, the solid base is at least one of HND-63, HND-64.

[0042] More specifically, the drying agent used in the drying treatment of acrylonitrile is at least one of anhydrous sodium sulfate, silica gel, neutral alumina, and molecular sieve.

[0043] More specifically, the solid base catalysts HND-63 and HND-64 used in the embodiments of the present application are purchased from Jiangyin Nandai Synthetic Chemical Co., Ltd.; and the hydrotalcite catalyst is purchased from Macklin Reagent Network.

[0044] Specifically, in step S2, the reaction temperature is 30-80℃.

[0045] Specifically, in step S2, the molar ratio of 1-amino-2-cyano-1-cyclopentene to dried acrylonitrile is 1:(0.9-1.3).

[0046] The mass ratio of 1-amino-2-cyano-1-cyclopentene to the solid base is 1:(0.02-0.2).

[0047] Specifically, in step S3, the dehydrating agent is at least one of phosphorus pentoxide, phosphorus oxychloride, and thionyl chloride.

[0048] Specifically, in step S3, the mass ratio of 1,3,6-hexanetricarbonitrile to the dehydrating agent is 1:(0.01-0.05).

[0049] In step S3, the reaction temperature is 50-120℃.

[0050] Specifically, in step S3, the post-treatment purification treatment is as follows: after the dehydration treatment, water washing is performed until neutral, and after the solvent is removed, distillation is performed, the pressure of the first-stage distillation is 5-30Pa, and the temperature is 150-190℃, the obtained heavy component is subjected to second-stage distillation, the pressure of the second-stage distillation is 5-30Pa, and the temperature is 190-230℃, and the obtained light component is the 1,3,6-hexanetricarbonitrile product.

[0051] More specifically, the solvent used in the preparation method of the 1,3,6-hexanetricarbonitrile in the embodiments of the present application is toluene, but this does not constitute a limitation on the present application.

[0052] I. Synthesis and preparation examples

[0053] Example 1

[0054] A method for preparing 1,3,6-hexanetricarbonitrile, the method comprising:

[0055] (1) Weigh 101 g (0.9 mol) of potassium tert-butoxide into a 2000 ml flask, add 1000 g of toluene, and pass a dry and stable nitrogen gas stream. Stir and heat to 90-100°C, and control the temperature to add 97.3 g (0.9 mol) of adiponitrile dropwise. The system gradually turns into a brownish yellow viscous solid-liquid mixture. After the dropwise addition, heat for 2 hours, cool to 40°C, and add 300 g of ice water. Filter at 20-30°C, and the filter cake is 1-amino-2-cyan-1-cyclopentene. Separate the filtrate, and remove the solvent from the organic phase to leave 150 g. Cool to 20-30°C, and filter to obtain a white solid 1-amino-2-cyan-1-cyclopentene 92.4 g (purity 99.8% by GC, yield 95%);

[0056] (2) Weigh 64.9 g (0.6 mol) of 1-amino-2-cyan-1-cyclopentene into a 1000 ml flask, add 300 g of toluene and 4 g of solid base catalyst HND-63, and stir and heat to 45-50°C. Control the temperature to add 35 g (0.66 mol) of acrylonitrile (water content ≤500 ppm) dried by molecular sieves dropwise. After the dropwise addition, heat for 3 hours, cool to 30°C, and filter to remove the catalyst to obtain a toluene solution of 1,3,6-hexanetricarbonitrile;

[0057] (3) Add 2.9 g of phosphorus pentoxide to the filtrate obtained in step (2), heat to 100°C, and heat for 3 hours. Cool to 30°C, wash with water until neutral, and remove the solvent to obtain 94.8 g of a yellowish viscous liquid 1,3,6-hexanetricarbonitrile (crude product, purity 98.2% by GC, yield 98%). Distill using a thin film distillation device, oil temperature 170°C, pressure 5-10 Pa, to obtain a primary heavy component (GC: 99.22%). Distill the primary heavy component using a thin film distillation device, oil temperature 195°C, pressure 5-10 Pa, to obtain a nearly colorless secondary light component, i.e. 1,3,6-hexanetricarbonitrile pure product (GC: 99.92%, colority 6 Hazen, water content 25 ppm), total yield 88.4%.

[0058] HRMS (ESI): C9H 11 N3, theoretical value: 161, found: 161.

[0059] 1 HNMR (400 MHZ, chloroform-d) δ (ppm): 1.77-2.01 (m, 6H), 2.40-2.47 (m, 1H), 2.51-2.66 (m, 2H), 2.74-2.83 (m, 1H);

[0060] 13CNMR (100 MHZ, deuterated chloroform) δ (ppm): 15.3, 16.7, 22.9, 27.8, 30.3, 30.5, 118.3, 119.1, 119.9.

[0061] The GC-MS spectrum of 1,3,6-hexanetricarbonitrile is shown in Figure 1 ; 13 The CNMR spectrum is shown in Figure 1 ; 1 The HNMR spectrum is shown in Figure 3 .

[0062] Example 2

[0063] A method for preparing 1,3,6-hexanetricarbonitrile, the method comprising:

[0064] (1) The method for preparing 1-amino-2-cyano-1-cyclopentene is the same as step (1) of Example 1;

[0065] (2) 64.9 g (0.6 mol) of 1-amino-2-cyano-1-cyclopentene was weighed into a 1000 ml three-necked flask, 300 g of toluene and 6.5 g of hydrotalcite solid base were added, and the mixture was stirred and heated to 55-60°C. After the temperature was controlled, 38.2 g (0.72 mol) of acrylonitrile (water content ≤500 ppm) dried by molecular sieves was added dropwise. After the dropwise addition was completed, the mixture was kept at 55-60°C for 3 hours. After the temperature was lowered to 30°C, the catalyst was filtered out to obtain a toluene solution of 1,3,6-hexanetricarbonitrile;

[0066] (3) 3.8 g of phosphorus pentoxide was added to the filtrate obtained in step (2), and the mixture was heated to 110°C and kept at this temperature for 3 hours. After the temperature was lowered to 30°C, the mixture was washed with water until it was neutral. After the solvent was removed, 95.2 g of a light yellow viscous liquid 1,3,6-hexanetricarbonitrile (crude product, GC purity 97.6%, yield 98.4%) was obtained. Thin film distillation was performed at an oil temperature of 170°C and a pressure of 5-10 Pa to obtain a primary heavy component (GC: 98.9%). The primary heavy component was subjected to secondary distillation using a thin film distillation device at an oil temperature of 190°C and a pressure of 5-10 Pa to obtain a nearly colorless secondary light component, i.e., a pure 1,3,6-hexanetricarbonitrile (GC: 99.90%, color 8 Hazen, water content 33 ppm), and the total yield was 86.7%.

[0067] Example 3

[0068] A method for preparing 1,3,6-hexanetricarbonitrile, the method comprising:

[0069] (1) The method for preparing 1-amino-2-cyano-1-cyclopentene is the same as step (1) of Example 1;

[0070] (2) Take 64.9 g (0.6 mol) of 1-amino-2-cyano-1-cyclopentene into a 1000 ml three-necked flask, add 300 g of toluene, 11 g of solid base catalyst HND-64, stir to warm to 70-75 °C, control the temperature and drop 35 g (0.66 mol) of acrylonitrile (water content ≤500 ppm) dried by molecular sieves; after dropping, keep warm for 3 h, cool to 30 °C, filter to remove the catalyst, and 1,3,6-hexanetricarbonitrile toluene solution is obtained;

[0071] (3) Add 2.9 g of phosphorus oxychloride to the filtrate obtained in step (2), warm to 110 °C and keep warm for 3 h, cool to 30 °C, wash with water until neutral, and remove the solvent to obtain 94 g of light yellow viscous liquid 1,3,6-hexanetricarbonitrile (crude product, GC detection purity 98.6%, yield 97.2%); use a thin film distillation device for distillation, oil temperature 170 °C, pressure 5-10 Pa, and distill to obtain primary heavy components (GC: 99.2%); use a thin film distillation device for secondary distillation of the primary heavy components, oil temperature 195 °C, pressure 5-10 Pa, and distill to obtain nearly colorless secondary light components, i.e. 1,3,6-hexanetricarbonitrile pure product (GC: 99.92%, colority 4 Hazen, water content 30 ppm), and the total yield is 88.3%.

[0072] Example 4

[0073] A method for preparing 1,3,6-hexanetricarbonitrile, the method comprising:

[0074] (1) Take 25.20 g (1.05 mol) of sodium hydride into a 2000 ml three-necked flask, add 1000 g of toluene, pass a dry and stable nitrogen gas stream, stir to warm to 40-50 °C, control the temperature and drop 75.70 g (0.7 mol) of adiponitrile, and the system gradually changes into a brownish yellow viscous solid-liquid mixture; after dropping, keep warm for 2 h, cool to 30 °C, add into 300 g of ice water, filter at 20-30 °C, and the filter cake is 1-amino-2-cyano-1-cyclopentene; filter the filtrate, remove the solvent from the organic phase to remain 150 g, cool to 20-30 °C, filter, and the obtained filter cake is combined with the above filter cake and dried to obtain white solid 1-amino-2-cyano-1-cyclopentene 71.7 g (GC detection purity 99.7%, yield 94.7%);

[0075] (2) Take 64.9 g (0.6 mol) of 1-amino-2-cyano-1-cyclopentene into a 1000 ml three-necked flask, add 300 g of toluene, 1.3 g of solid base catalyst HND-63, stir to warm to 70-80 °C, control the temperature and drop 41.38 g (0.78 mol) of acrylonitrile (water content ≤500 ppm) dried by molecular sieves; after dropping, keep warm for 3 h, cool to 30 °C, filter to remove the catalyst, and 1,3,6-hexanetricarbonitrile toluene solution is obtained;

[0076] (3) To the filtrate obtained in step (2), 4.8 g of phosphorus oxychloride was added, and the temperature was raised to 120°C and maintained for 2 h. After the temperature was lowered to 30°C, the solution was washed with water until it was neutral, and the solvent was removed to obtain 94.5 g of a light yellow viscous liquid, 1,3,6-hexanetricarbonitrile (crude product, GC purity 97.7%, yield 98%). The crude product was distilled using a thin film distillation device at an oil temperature of 190°C and a pressure of 25-30 Pa to obtain a primary heavy component (GC: 99.20%). The primary heavy component was subjected to secondary distillation using a thin film distillation device at an oil temperature of 230°C and a pressure of 25-30 Pa to obtain a nearly colorless secondary light component, i.e., 1,3,6-hexanetricarbonitrile (GC: 99.90%, color 6 Hazen, water content 26 ppm), which was the pure product. The total yield was 88.2%.

[0077] Example 5

[0078] A method for preparing 1,3,6-hexanetricarbonitrile, the method comprising:

[0079] (1) 86.49 g (0.9 mol) of potassium tert-butoxide was weighed into a 2000 ml flask, 1000 g of toluene was added, and a dry and stable nitrogen gas stream was introduced while stirring. The temperature was raised to 40-50°C, and 81.11 g (0.75 mol) of hexanedicarbonitrile was added dropwise while controlling the temperature. The system gradually changed to a brownish yellow viscous solid-liquid mixture. After the dropwise addition was completed, the temperature was maintained for 3 h, and 300 g of ice water was added at a temperature of 40°C or lower. The mixture was filtered at a temperature of 20-30°C to obtain 1-amino-2-cyano-1-cyclopentene as a filter cake. The filtrate was separated into an organic phase and an aqueous phase, and the organic phase was subjected to solvent removal to obtain 150 g of a residue. The residue was filtered at a temperature of 20-30°C to obtain 76.89 g of 1-amino-2-cyano-1-cyclopentene as a white solid (GC purity 99.8%, yield 94.8%);

[0080] (2) 64.9 g (0.6 mol) of 1-amino-2-cyano-1-cyclopentene was weighed into a 1000 ml flask, 300 g of toluene and 12.9 g of a solid base catalyst HND-64 were added, and the temperature was raised to 30-40°C while stirring. 38.2 g (0.72 mol) of acrylonitrile (water content ≤ 500 ppm) was added dropwise while controlling the temperature. After the dropwise addition was completed, the temperature was maintained for 4 h, and the catalyst was removed by filtration at a temperature of 30°C or lower to obtain a toluene solution of 1,3,6-hexanetricarbonitrile.

[0081] (3) To the filtrate obtained in step (2), 1.94 g of thionyl chloride was added, and the temperature was raised to 50 °C for 4 h. After the temperature was lowered to 30 °C, the solution was washed with water until neutral, and desolvated to obtain 95.3 g of a light yellow viscous liquid 1,3,6-hexanetricarbonitrile (crude product, GC purity 98.0%, yield 98.5%); distillation was performed using a thin film distillation device, oil temperature 150 °C, pressure 10-15 Pa, to obtain a primary heavy component (GC: 99.0%); the primary heavy component was subjected to secondary distillation using a thin film distillation device, oil temperature 200 °C, pressure 10-15 Pa, to obtain a nearly colorless secondary light component, i.e. 1,3,6-hexanetricarbonitrile pure product (GC: 99.91%, colority 5 Hazen, water content 30 ppm), total yield 87.0%.

[0082] Comparative Example 1

[0083] 1,3,6-hexanetricarbonitrile was prepared by the same method as in Example 1, except that in step (2) of Comparative Example 1, 120 g of 40% sodium hydroxide aqueous solution was used. After the reaction of Comparative Example 1 was completed, the purity of the crude 1,3,6-hexanetricarbonitrile was 91.2%, the purity of the final 1,3,6-hexanetricarbonitrile was 98.7%, the colority was 33 Hazen, and the total yield was 65%;

[0084] From the comparison of the experimental data of Comparative Example 1 and Example 1, it can be seen that if the base is replaced by sodium hydroxide aqueous solution, the water content in the reaction system is higher, which will lead to more acrylonitrile hydrolysis to 3-hydroxypropionitrile, and then reaction with acrylonitrile to generate 2-cyanoethyl ether; at the same time, the system is a strong alkali system of sodium hydroxide aqueous solution, which will have more product hydrolysis to amide impurities; resulting in lower purity of the final product, worse colority, and lower yield.

[0085] Comparative Example 2

[0086] 1,3,6-hexanetricarbonitrile was prepared by the same method as in Example 1, except that in step (2) of Comparative Example 2, the acrylonitrile used was directly purchased acrylonitrile without drying, and the water content of the acrylonitrile was 3500 ppm. After the reaction of Comparative Example 2 was completed, the purity of the crude 1,3,6-hexanetricarbonitrile was 95.9%; the purity of the final 1,3,6-hexanetricarbonitrile was 99.78%, the colority was 12 Hazen, and the total yield was 76.5%;

[0087] From the comparison of the experimental data of Comparative Example 2 and Example 1, it can be seen that the water content of acrylonitrile is higher, which will also generate more 2-cyanoethyl ether and amide impurities, resulting in lower purity of the final product, worse colority, and lower yield.

[0088] Comparative Example 3

[0089] The same method as in Example 1 was used to prepare 1,3,6-hexanetricarbonitrile, except that in step (3) of Comparative Example 3, the reaction solution was not treated with phosphorus pentoxide, and the purity of the final 1,3,6-hexanetricarbonitrile was 99.62%, the color was 17 Hazen, and the total yield was 86.3%;

[0090] As can be seen from the experimental data of Comparative Example 3 and Example 1, even if a solid base is used and the acrylonitrile is dried, there will still be a small amount of water remaining in the system, and if the reaction solution is not treated with phosphorus pentoxide, there will be a small amount of amide impurity in the system after the reaction, which will cause the purity of the final product to decrease and the color to deteriorate.

[0091] II. Long-term stability test of the product

[0092] The 1,3,6-hexanetricarbonitrile obtained in Examples 1-5 and Comparative Examples 1-3 was stored at 30°C and 60°C, respectively, and the color was tracked periodically. The relevant test data are shown in Table 1.

[0093] Table 1: Results of the long-term stability test of the product

[0094]

[0095] As can be seen from the above table data, the 1,3,6-hexanetricarbonitrile prepared by the method described in Examples 1-5 is more suitable for long-term storage and has stable color, and is more suitable for application in lithium battery electrolyte as a lithium battery electrolyte additive.

[0096] The technical features of the above-described examples can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described examples are described, but as long as the combinations of the technical features do not contradict each other, they should be considered as within the scope of the present disclosure.

[0097] The above-described examples only express several embodiments of the present application, and the description is more specific and detailed, but it should not be construed as limiting the scope of the patent. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of protection of the present patent should be subject to the appended claims.

Claims

1. A process for the preparation of 1,3,6-hexanetricarbonitrile, characterized in that, The preparation method is: S1, under the condition of non-nucleophilic strong base, 1-amino-2-cyano-1-cyclopentene is prepared from adiponitrile as raw material and dried by baking; S2, in the presence of solid base, 1-amino-2-cyano-1-cyclopentene reacts with dried acrylonitrile to obtain a reaction solution; S3, using dehydrating agent for 1,3,6-hexane tricyanate reaction solution dehydration treatment, finally after treatment purification to obtain 1,3,6-hexane tricyanate product.

2. The process for the preparation of 1,3,6-hexanetricarbonitrile according to claim 1, characterized in that, In step S1, the non-nucleophilic strong base is at least one of potassium tert-butoxide, sodium tert-butoxide, potassium tert-amylate, sodium tert-amylate, sodium hydride, and sodium amide.

3. The process for the preparation of 1,3,6-hexanetricarbonitrile according to claim 1, characterized in that, In step S1, the molar ratio of non-nucleophilic strong base to adiponitrile is (1-1.5):

1.

4. The process for the preparation of 1,3,6-hexanetricarbonitrile according to claim 1, characterized in that, In step S1, the reaction temperature is 40-100℃.

5. The process for the preparation of 1,3,6-hexanetricarbonitrile according to claim 1, characterized by, In step S2, the solid base is at least one of hydrotalcite catalyst, HND-63, and HND-64; The water content in dried acrylonitrile is ≤500ppm.

6. The process for the preparation of 1,3,6-hexanetricarbonitrile according to claim 1, characterized by, In step S2, the reaction temperature is 30-80℃.

7. The process for the preparation of 1,3,6-hexanetricarbonitrile as claimed in claim 1, wherein, In step S2, the molar ratio of 1-amino-2-cyano-1-cyclopentene to dried acrylonitrile is 1:(0.9-1.3); The mass ratio of 1-amino-2-cyano-1-cyclopentene to solid base is 1:(0.02-0.2).

8. The process for the preparation of 1,3,6-hexanetricarbonitrile according to claim 1, characterized by, In step S3, the dehydrating agent is at least one of phosphorus pentoxide, phosphorus oxychloride, and thionyl chloride.

9. The process for the preparation of 1,3,6-hexanetricarbonitrile according to claim 1, characterized by, In step S3, the mass ratio of 1,3,6-hexane tricyanate to dehydrating agent is 1:(0.01-0.05); In step S3, the reaction temperature is 50-120℃.

10. The process for the preparation of 1,3,6-hexanetricarbonitrile as claimed in claim 1, wherein, In step S3, the post-treatment purification treatment is: after dehydration treatment, water washing to neutral, after desolventizing, distillation, the first distillation pressure is 5-30Pa, the temperature is 150-190℃, the obtained heavy component is subjected to secondary distillation; the secondary distillation pressure is 5-30Pa, the temperature is 190-230℃, and the obtained light component is the 1,3,6-hexane tricyanate product.

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